Aqueous dispersions based on heathardenable phenolic resins containing a gum mixture stabilizing agent

ABSTRACT

THE DISCLOSURE OF THIS APPLICATION IS DIRECTED TO AQUEOUS DISPERSIONS OF HEAT-HARDENABLE PHENOLIC RESINS, WHICH ARE CHARACTERIZED BY EXCELLENT STABILITY, BY A LOW POLLUTION INDEX, ARE CAPABLE OF BEING INFINITELY DILUTED WITH WATET AND ARE ESPECIALLY DESIRABLE FOR USE IN APPLICATIONS WHERE: IN MINERALS FIBERS ARE SPARYED WITH THE AQUEOUS DISPERSIONS AND SUBSEQUENTLY FORMED INTO MINERAL FIBER BATTS.

United States Patent US. Cl. 260--17.2 13 Claims ABSTRACT OF THE DISCLOSURE The disclosure of this application is directed to aqueous dispersions of heat-hardenable phenolic resins, which are characterized by excellent stability, by a low Pollution Index, are capable of being infinitely diluted with water and are especially desirable for use in applications wherein mineral fibers are sprayed with the aqueous dispersions and subsequently formed into mineral fiber batts.

This application is a continuation-in-part of my copending application Ser. No. 164,8 19, filed July 21, 1971, now abandoned.

This invention relates to aqueous dispersions based on heat-hardenable phenolic resins. More particularly, this invention relates to aqueous dispersions of heat-hardenable phenolic resins, which are characterized by excellent stability, by a low pollution index and are capable of being infinitely diluted with water. In view of the properties noted above and, also, in view of the excellent adhesion to glass, when cured, the aqueous dispersions of this invention have particular utility in applications wherein mineral fibers are sprayed with the aqueous dispersions and subsequently formed into mineral fiber batts and other such compacted structures.

Mineral fiber batts and other such compacted structures, which have found wide acceptance in the fields of thermal and acoustical insulation, have been produced by first blowing a stream of molten glass or slag with high pressure steam in such a manner that the glass or slag stream is drawn into fibers of random lengths. The fibers, while in transit in a forming hood or blow chamber and while still at elevated temperatures from the drawing operation, have then been sprayed with an aqueous solution of a heat-hardenable phenolic resin and thereafter allowed to settle into a continuous mat on an endless foraminous conveyer belt. Generally, there is sufficient residual heat in the mineral fibers to volatilize substantially all of the water from the phenolic binder, leaving the binder on the fibers in a viscous or semi-viscous state. The sprayed fibers, in the form of a batt, have then been transferred to a curing oven, heated by air which is at relatively high temperatures, about 400 F. and which is blown through the batt. The relatively high temperatures involved effect a cure of the binder to an infusible state.

At the relatively high temperatures employed in this process, the low molecular weight components of the water-soluble phenolic resin tend to volatilize, escape to, and pollute the atmosphere. Consequently, the use of water-soluble, heat-hardenable phenolic resins as binders in the production of fiber batts, is being severely restricted in view of the current pollution standards now in elfect in many areas of the country.

Attempts to utilize phenolic resins made up of molecules of higher molecular weight, in the form of aqueous dispersions, in order to minimize volatilization have not proved to be particularly successful. Such dispersions have poor stability characteristics as the phenolic resin thereof 3,823,103 Patented July 9, 1974 settles out within a few minutes after preparation, coalescing into a continuous resin phase. Furthermore, such dis persions cannot be diluted with water to a consistency suitable for use in spray applications.

The present invention provides aqueous dispersions which can be successfully used in the production of ,mineral fiber batts by a spray operation, the dispersions being characterized by excellent bonding and application efiiciency. The aqueous dispersions of this invention exhibit a tensile strength of at least about 300 psi. when tested according to the Glass Adhesion Test described subsequently in this specification. Also, the aqueous dispersions remain stable for periods of time in excess of about 2 weeks, that is, the phenolic resin particles thereof do not settle out into a continuous resin phase. Consequently, the dispersions can be prepared, shipped to the ultimate user and stored for extended periods of time. Further, the aqueous dispersions of this invention can be infinitely diluted with water to any desired concentration of phenolic resin solids with substantially no change in the size and uniformity of the dispersed resin particles therein. Furthermore, the aqueous dispersions of this invention retain the excellent properties discussed above and also retain their flow and gel properties for extended periods of time in contrast to the water soluble phenolic resins. Also, the aqueous dispersion of this invention have a pollution index of less than about 6 percent which is acceptable from an environmental standpoint, based on standards currently in force.

The aqueous dispersions of this invention contain a heat-hardenable phenolic resin having a weight average molecular weight of at least about 400, generally about 500 to about 3000 and preferably about 500 to about 2000.

Particularly desirable aqueous dispersions are those having a gel time of not more than about 180 seconds, generally about 10 to about 170 seconds, preferably about 20 to about 150 seconds and more preferably about 30 to about seconds, wherein the heat-hardenable phenolic resin thereof has a weight average molecular weight as defined above and wherein substantially all of the resin particles have a diameter of less than about 60 microns. Even more desirable aqueous dispersions are thoseas defined in the preceding paragraph wherein the resin particles have a diameter on average of about 5 to about 20 microns with substantially all resin particles having a diameter less than about 40 microns.

The heat-hardenable phenolic resins, used to produce the aqueous dispersions of this invention are resole resins obtained by condensing a phenol with an aldehyde in the presence of an alkaline catalyst.

Among suitable phenols which can be condensed with an aldehyde to produce phenol-aldehyde resole resins are the monohydric as well as the polyhydric phenols.

Among suitable monohydric phenols can be noted; phenol and those phenols having the general formula:

Formula I wherein x is an integer having a value of 1 to 2 inclusive, each R, which can be the same or different, is an alkyl radical containing from 1 to 9 carbon atoms inclusive, an alkoxy radical containing from 1 to 9 carbon atoms inclusive, or a halogen, e.g. chlorine, bromine and iodine; with the proviso that at least three positions other than meta to the hydroxyl group are unsubstituted.

Specific phenols falling within the scope of Formula I are: alkylated phenols, exemplary of which are m-cresol, m-ethylphenol, m-propylphenol, m-isopropylphehol, msec-butylphenol, m-amylphenol, m-hexylphenol, gg-nonylphenol and other like phenols, as well as the commercially available meta-cresol which contains small amounts of both the para and the ortho isomers; alkoxylated phenols, exemplary of which are n -methoxyphenol, m-ethoxyphenol, 1n -propoxyphenol, m-hexoxyphenol, 3,5-dimethoxyphenol, and the like; halogenated phenols such as meta-chlorophenol, meta-bromophenol, and the like.

Among suitable polyhydric phenols can be noted res orcinol, and the like, as well as polyhydric, polynuclear phenols having the formula:

Formula 2 wherein Z is a divalent radical, as for example, sulfur, oxygen, alkylidene, alkylene and the like; and also substituted derivatives of phenols falling with the scope of Formula 2.

Exemplary of specific polyhydric, polynuclear phenols are the following: bis(hydroxyphenyl)alkanes such as 2,2-bis(4-hydroxyphenyl)propane, commonly referred to as Bisphenol A, 2,4-dihydroxydiphenylmethane, dihydroxydiphenyl sulfone and the like.

Also small amounts of diand/or mono-functional phenols such as p-nonylphenol and 2,5-di-tert-butylphe- 1101 can be used in conjunction with tri and higher functional phenols, illustrated above, to produce suitable phenolic resins for purposes of this invention.

Examples of aldehydes which can be condensed with the phenols listed above to produce the phenol-aldehyde resins are: formaldehyde in any of its available forms, i.e., formalin and para-formaldehyde; furfural and the like.

The amount of aldehyde used to prepare the heat-hardenable or resole resins of this invention is at least about 0.9 mole per mole of phenol, generally about 1 to about 3 moles and preferably about 1.2 to about 2.5 moles per mole of phenol.

As previously stated, the condensation of a phenol and an aldehyde is carried out in a reaction medium containing an alkaline catalyst. Illustrative of suitable catalysts are the following: alkali metal and alkaline earth metal hydroxides or oxides, as for example, sodium hydroxide, potassium hydroxide, calcium hydroxide, calcium oxide, barium hydroxide, barium oxide and the like, or an amine such as hexamethylenetetramine or ammonia.

Particularly desirable resins for purposes of this invention are those produced using barium hydroxide as a catalyst. An aqueous dispersion of such resin when applied to mineral fibers and cured, exhibits an unusually high degree of adhesiveness thereto.

The amount of catalyst used in producing the resole resins is about 0.01 to about 0.1 mole per mole of phenol, preferably about 0.02 to about 0.05 mole per mole of phenol. For a detailed discussion of condensates produced from a phenol and an aldehyde and methods for the production thereof, reference is made to the following: "Phenolic Resins by W. A. Keutgen, Encyclopedia of Polymer Science & Technology, Volume 10, pages 1- 73, published by lnterscience, John Wiley-l969'.

The preparation of the aqueous dispersions of this invention can be carried out by a number of convenient methods, as for example by condensing a phenol with an aldehyde in a reaction mixture containing an alkaline catalyst to produce a heat-hardenable phenolic resin, adding to the mixture, a mixture of gums, as will be described subsequently and adjusting the pH of the resultant mixture, if necessary to less than about 8, generally to a pH of about 3 to about 7.5 and preferably to a pH of about 4.5 to about 6.5 and then condensing (bodying) the resin, if necessary, to a weight average molecular weight as previously described.

Alternatively, the pH of the mixture can be adjusted, if necessary, prior to the addition of the gums, the gums then added and the resin then bodied as indicated above. Also, the gums can be added, along with the phenol, aldehyde and alkaline catalyst, into the reaction flask and 4 this mixture condensed and bodied, as described above.

With each of the methods described, the aqueous dispersion produced has a pH of less than about 8 generally about 3 to about 7.5 and preferably about 4.5 to about 6.5.

The gums which are used to prepare the aqueous dispersions are a mixture of gum arabic and one or more of the following gums: (l) a polysaccharide having mannose and galactose units, particularly desirable polysaccharides being a guar gum, a locust bean gum and the like. Guar gums are available commercially from Stein Hall & Co. under the designation Jaguar gums (2) a polysaccharide having D-mannuronic acid and L-guluronic acid units, particularly desirable polysaccharides being an algin gum and the like.

The combined weight of the gums used in producing the aqueous dispersions is about 0.5 to about 12, preferably about 0.5 to about 10 and more preferably about 1.2 to about 4.5 parts -by weight based on each parts by weight phenol used in producing the heat-hardenable phenolic resin. The weight ratio of gum arabic to the other recited gums is about 0.5 to about 20 to 1, preferably about 0.5 to about 16 to 1 and more preferably about 1 to about 5 to 1.

The production of the dispersions of this invention is further exemplified by the Examples noted in the specification wherein the gums are utilized in the form of aqueous solutions or in the dry form.

'In utilizing the dispersions of this invention for mineral fiber bonding by a spray application wherein the solid resins content is on the order of about 2 to about 20 percent by weight, it is customary to add thereto such additives as flame-retardants, exemplary of which are urea and the like, silane coupling agents and other ad ditives well known in the art. Silane coupling agents are generally used in amounts of about 0.1 percent to about 0.5 percent by weight based on the solids content of the aqueous dispersion. Among suitable silanes are the trialkoxy amino alkyl silanes wherein a nitrogen atom thereof is separated from a silicon atom by at least three sequential carbon atoms. Specific silanes are the following:

HzNCHzCHgCH: S l\0 GHQ-gamma-amlnopropyl trlmethoxy a silane; H

l HzNOHzCHgNCHzCHgOHg S 1(0 CHs)a-N(beta-amlnoethyl)- gamma-amino-propyl trimethoxy silane; H H

HzN 0 H5 3 H CH1 S i O CzHs) -gamma-amino-2-rnethyl propyl trlethoxy silane; and H2 2)a S i( HQa-delta-amlno butyl trimethoxy silane A particularly desirable silane is one used in carrying out the Glass Adhesion Test.

Although the aqueous dispersions of this invention have been described primarily in relation to spray applications to produce mineral fiber batts suitable as thermal and acoustical insulation, the aqueous dispersions can be used as laminating varnishes, additives to paper and other cellulosic pulp and in general, in bonding applications, to bond together organic and inorganic particles and fibers.

In the following examples, which are illustrative of the present invention, properties noted therein were determined by the following procedures.

Gel Timedetermined by placing a two gram sample of the aqueous dispersion on a hot plate which was at a temperature of C. The resin was stroked with a spatula and the time required to reach a no string condition noted and reported as the Gel Time. A no string condition is reached when there is no pulling of strings of the material, by the spatula, from the main body of the resin.

Pollution Index-determined by weighing a two gram sample of the dispersion into a weighed tin. To the sample, there was then added 15 ml. analytical grade methanol and the contents of the tin thoroughly mixed. The tin, containing the sample, was placed in a 300 F. oven for 2 hours. At the end of the two hour period, the tin was removed from the oven and placed in a desiccator wherein the tin and the residue cooled to room temperature. The tin, containing the residue, was weighed and the weight of the residue recorded. Tin and residue were then placed in a 450 F. oven for 20 minutes. The tin, with the residue therein, was removed from the oven, cooled to room temperature in a desiccator and reweighed. Percent weight loss of the residue, resulting from the heating cycle in the 450 F. oven was calculated and re ported as the Pollution Index. A Pollution Index below about six percent is acceptable from an environment standpoint.

Glass Adhesion Test-the composition to be tested, based on the aqueous dispersion of Example I had the following formulation:

The composition was prepared by weighing the water into a 100 ml. beaker and adding the ammonium sulfate thereto. The mixture was stirred to solution and to this solution there was then added in sequence, the aqueous dispersion, the urea and silane. The pH of the ultimate mixture was adjusted to 8.2 by the addition thereto of ammonium hydroxide. The composition was charged into a Hobart mixer which contained 582 grams of small glass beads (designated as P-93 Glass Spheres by the supplier, Cataphote Corp.). The materials were thoroughly mixed and the mixture then poured into a mold, having a number of dog-bone shaped cavities, which had been preheated in a 450 F. oven. The filled mold was placed in the 450 F. oven for 5 minutes. Test specimens were then removed from the mold, half placed in a desiccator and the other half placed in a humidity chamber wherein the relative humidity was 100% and the temperature was 120 F.

Binder content of each specimen was 3 percent by weight.

Specimens were aged and tested for tensile strength which is indicative of bonding strength, using a Baldwin Tensile Tester with the cross-head speed set at 0.2 inch per minute.

The silane used in the formulation had the following structure:

Molecular Weight Distribution=Mw/I\In Number Average Molecular Weight: (Mn) and Weight Average Molecular Weight: (MW) determined according to procedure described in J. Polymer Science, A 835, 1964, by J. Moore.

Particle Size of Resin in the Aqueous Dispersiondetermined using a Coulter Counter.

EXAMPLE 1 Into a five liter, round bottom flask, equipped with a reflux condenser, agitator, thermometer and heating mantle, there was charged 1200 grams of phenol, 1668 grams aqueous formaldehyde (40%) and 30 grams of barium hydroxide monohydrate. The mixture was then heated to a temperature of 75 C. whereupon the heating mantle was removed and the mixture allowed to reach a stage of atmospheric reflux through its exothermic heat of reaction. The mixture was then allowed to reflux for about forty-five minutes. At the end of the forty-five minute period, a water solution, made up of 24 grams of gum arabic, -6 grams of guar gum and 720 grams of water, was added to the contents of the flask. After the addition of the gum there was then added, to the flask, a water solution, made up of 10 grams of sulfuric acid (96.6%) and 40 grams of water whereby the barium hydroxide was neutralized. The contents of the flask were then brought to a temperature of about C. and maintained at this temperature for about 10 minutes. At the end of the 10 minute period, the contents of the reaction flask were cooled to a temperature of about 50 C. and discharged into a container as a resin-in-water dispersion having a solids content of 42 percent by weight.

Solids content of the aqueous dispersions, as noted in this specification, was determined by placing a weighed sample of the dispersion in a 300 F. oven for 2 hours and weighing the residue after the 2 hour period. Percent solids was calculated by dividing the weight of the residue by the weight of the sample and multiplying by 100.

Properties of the phenol-formaldehyde resin:

Mole ratio of reactants-formaldehyde to phenol 1.75 to 1 The particles were excellently dispersed in the aqueous medium, as determined by microscopic examination.

pH of the aqueous dispersion 5.7 Pollution Index of the aqueous dispersion percent 2.9

The aqueous dispersion had excellent stabilit characteristics--no visual settling of particles after two weeks storage at a temperature of about 23 C. Also, the dispersion could be infinitely diluted with water without significant change as to particle size.

Glass Adhesion Test:

Average value of 6 test specimens (aged 1 hr.

in desiccator) 700 Average value of 6 test specimens (aged 16 hours in humidity chamber) 600 P.s.i.

On the basis of parts by weight phenol charged into the reaction flask, the amount of gum arabic in the dispersion was 2 parts by weight and the amount of guar gum, 0.5 parts by weight.

The guar gum noted in this and in subsequent examples is a commercial product sold by Stein-Hall under the designation Jaguar J2S1.

EXAMPLE 2 Into a five liter, round bottom flask, equipped with a reflux condenser, agitator, thermometer and heating mantle, there was charged 720 grams of water, 24 grams of gum arabic and 6 grams of guar gum. The materials were mixed for 15 minutes and to the mixture there was then added 1200 grams of phenol, 1668 grams of aqueous formaldehyde (40%) and 48 grams of aqueous sodium hydroxide (25%). The mixture was then heated to a temperature of 75 C. whereupon the heating mantle was removed and the mixture allowed to reach a stage of reflux through its exothermic heat of reaction. The mixture was then allowed to reflux for about forty-five minutes. At the end of the forty-five minute period, the reacted mixture was cooled to a temperature of 85 C. and an aqueous mixture, made up of 15.6 grams of aqueous phosphoric acid (85%) and 36 grams of water, added thereto. After 1.5 hours at a temperature of 85 C., the contents of the flask were discharged into a container as a resinin-water dispersion having a solids content of 42.2 percent by weight.

Properties of the phenol-formaldehyde resin:

Mole ratio of reactantsformaldehyde to phenol 1.75 to 1 Number average molecular weight 330 Weight average molecular weight 1500 Molecular weight distribution 4.5 Gel time "seconds" 76 The size of the resin particles, dispersion thereof in the aqueous medium and the stability and the dilutability characteristics of the aqueous dispersion were comparable to those of Example 1.

pH of the aqueous dispersion 6.75 Pollution Index of the aqueous dispersion -percent-.. 3.3

On the basis of 100 parts by weight phenol charged into the reaction flask, the amount of gum arabic used was 2 parts by weight and the amount of guar gum, 0.5 parts by weight.

EXAMPLE 3 The procedure of Example 1 was repeated using the materials and amounts thereof as noted below. This example differs primarily from Example 1 in that a smaller amount of formaldehyde was used, sodium hydroxide was the catalyst and phosphoric acid, the neutralizing agent.

Amount in grams Phenol 1200 Formaldehyde (40% aqueous solution) 1332 Sodium hydroxide (25% aqueous solution) 48 Gum arabic 24 Guar gum 6 Water 720 Phosphoric acid (85%) 15.6 Water 36 Solids content of the resin-in-water dispersion was 45.6 percent by weight.

Properties of the phenol-formaldehyde resin:

Mole ratio of reactants-formaldehyde to phenol 1.40 to 1 Number average molecular weight 380 Weight average molecular weight 990 Molecular weight distribution 2.6 Gel time seconds 58 The size of the resin particles, dispersion thereof in the aqueous medium and the stability and dilutability characteristics of the aqueous dispersion were comparable to those of Example 1.

pH of the aqueous dispersion 6.5 Pollution Index of the aqueous dispersion "percent" 2.8

On the basis of 100 parts by weight phenol charged into the reaction flask, the amount of gum arabic used was 2 parts by Weight and the amount of guar gum, 0.5 parts by weight.

EXAMPLE 4 The procedure of Example 1 was repeated using the materials and amounts thereof as noted below. This example differs primarily, from Example 1 in that a larger amount of formaldehyde was used, sodium hydroxide was the catalyst and phosphoric acid, the neutralizing agent.

Amount in grams Phenol 1100 Formaldehyde (40% aqueous solution) 1760 Sodium hydroxide (25% aqueous solution) 44 Gum arabic v 22 Guar gum 5.5 Water 600 Phosphoric acid 14.3 Water 33 The solids content of the resin-in-water dispersion was 42.3 percent by weight.

Properties of the phenol-formaldehyde resin:

Mole ratio of reactantsformaldehyde to phenol 2.01 to 1 Number average molecular weight 340 Weight average molecular weight 850 Molecular Weight distribution 2.5 Gel time seconds 59 The size of the resin particles, dispersion thereof in the aqueous medium and the stability and dilutability characteristics of the aqueous dispersion were comparable to those of Example 1.

pH of the aqueous dispersion 6.6 Polution Index of the aqueous dispersion percent 3.7

On the basis of parts by weight phenol charged into the reaction flask, the amount of gum arabic used was 2 parts by weight and the amount of guar gum, 0.5 parts by weight.

EXAMPLE 5 The procedure of Example 1 was repeated using the materials and amounts thereof as noted below. This example differs primarily from Example 1 in that sodium hydroxide was used as the catalyst and hydrochloric acid was used as the neutralizing agent.

Amount in grams The size and uniformity of the resin particles, dispersion thereof in the aqueous medium and the stability of the aqueous dispersion were comparable to those of Example 1.

pH of the aqueous dispersion 6.7 Pollution Index of the aqueous dispersion percent 3.5

On the basis of 100 parts by weight phenol charged into the reaction flask, the amount of gum arabic used was 2 parts by Weight, the amount of guar gum, 0.5 parts by weight.

EXAMPLES 6-8 The procedure of Example 1 was repeated, using in each instance, various amounts of gum arabic and guar gum. Amounts used, in parts by weight, based on 100 parts by weight of phenol charged into the reaction flask, are noted below:

Properties of these dispersions were comparable to properties of the dispersion of Example 1.

EXAMPLE 9 The procedure of Example 1 was repeated using the materials and amounts thereof as noted below. This example differs, primarily, from Example 1 in that a mixture of phenol and p-nonylphenol was used.

Amount in grams Phenol 360 p-Nonylphenol 40 Formaldehyde (40% aqueous solution) 520 Barium hydroxide monohydrate 10 Gum arabic 2 Guar gum 3 Water 270 Sulfuric acid (96.6%) 3.33 Water 13 The solids content of the resin-in-water dispersion was 42.1 percent by weight.

Properties of the phenol-formaldehyde resin:

Mole ratio of reactants-frmaldehyde to phenol 1.75 to 1 Number average molecular weight 410 Weight average molecular weight 1440 Molecular weight distribution 3.5 Gel time seconds '60 The size of the resin particles, dispersion thereof in the aqueous medium and the stability and dilutability characteristics of the aqueous dispersion were comparable to those of Example 1.

pH of the aqueous dispersion 6.4 Pollution Index of the aqueous dispersion percent 3.2 Glass Adhesion Test:

Average value of 6 test specimens (aged 1 hr.

in desiccator) p.s.i 600 Average value of 6 test specimens (aged 16 hrs.

in humidity chamber) p.s.i 625 The formulation of the composition tested using the aqueous dispersion of this example was as follows:

Grams Aqueous dispersion 33.73 Ammonium sulfate 0.2 Urea 3.6 Silane 0.54 Water 7.4

Amounts of glass beads used was 582 grams and the resin content of each composite or structure produced was 3% by weight.

On the basis of 100 parts by weight phenols charged into the reaction flask, the amount of gum arabic used was 0.5 parts by weight and the amount of guar gum, 0.75 parts by weight.

EXAMPLE 10 Example 1 was repeated with the exception that the mole ratio of formaldehyde to phenol was 1.89 to 1 and 10 in lieu of the gums of Example 1, the following gums were used, in the amounts noted, based on parts by weight of phenol charged:

Parts by weight Gum arabic 2 Algin gum 1 The algin gum of this example was obtained from Marine Colloids, Inc., under the trade designation Viscarin 402.

Properties of the phenol-formaldehyde resin:

Mole ration of reactants formaldehyde to phenol 1.89 to 1 Number average molecular weight 310 Weight average molecular weight 870 Molecular weight distribution 2.8 Gel trne seconds Solids content of resin-in-water dispersion percent by weight" 45 The size of the resin particles, dispersion thereof in the aqueous medium and the stability and dilutability characteristics of the aqueous dispersion were comparable to those of Example 1.

pH of the aqueous dispersion 5.4 Pollution Index of the aqueous dispersion percent 3.4

EXAMPLE 11 Example 1 was repeated using, in lieu of the guar gum, locust bean gum in the same weight relationship.

Properties of the phenol-formaldehyde resin:

Mole ratio of reactantsformaldehyde to phenol 1.75 to 1 Number average molecular weight 420 Weight average molecular weight 1930 Molecular weight distribution 4.6 Gel time seconds 75 Solids content of resin-in-water dispersion percent by weight..- 41

The size of the resin particles, dispersion thereof in the aqueous medium and the stability and dilutability characteristics of the aqueous dispersion were comparable to those of Example 1.

pH of the aqueous dispersion 5.5 Pollution Index of the aqueous dispersion percent 3.5

EXAMPLE 12 Example 1 was repeated using, in lieu of the guar gum of Example 1, Jaguar 1212A, a guar gum obtained from Stein-Hall, in the same weight relationship.

Properties of the phenol-formaldehyde resin:

Mole ratio of reactantsformaldehyde to phenol 1.75 tol Number average molecular weight 410 Weight average molecular weight 1760 Molecular weight distribution 4.3 Gel time seconds 80 Parfticle size (diameter) of the resin in the dispersion, on average microns 15 Diameter or substantially all of the particles of the resin in the dispersion do.. 30 Solids content of resin-in-water dispersion percent by weight 41 The size of the resin particles, dispersion thereof in the aqueous medium and the stability and dilutability charac- 11 teristics of the aqueous dispersion were comparable to those of Example 1.

pH of the aqueous dispersion 5.75 Pollution Index of the aqueous dispersion percent 3.4

EXAMPLE 13 The procedure of Example 1 was repeated using the materials and amounts thereof as noted below.

Amounts in grams Phenol 1200 Formaldehyde (40% aqueous solution 1332 Barium hydroxide monohydrate 30 Gum arabic 24 Guar gum 6 Sulfuric acid (20%) 63 Water 792 Solids content of the resin-in-water dispersion was 41 percent by weight.

Properties of the phenol-formaldehyde resin: Mole ratio of reactants-formaldehyde The size of the resin particles, dispersion thereof in the aqueous medium and the stability and dilutability characteristics of the aqueous dispersion were comparable to those of Example 1.

pH of the aqueous dispersion 5.0 Pollution Index of the aqueous dispersion percent 3.2

EXAMPLE 14 Into a five liter, round bottom flask, equipped with a reflux condenser, agitator, thermometer and heating mantle, there was charged 1200 grams of phenol, 1332 grams aqueous formaldehyde (40%), 30 grams of barium hydroxide monohydrate, 24 grams of gum arabic and 6 grams of guar gum. The resultant mixture was then heated to a temperature of about 75 C. whereupon the heating mantle was removed and the mixture allowed to reach a stage of atmospheric reflux through its exothermic heat of reaction. The mixture was then allowed to reflux for about 35 minutes. At the end of the 35 minute period, 792 grams of water were added to the contents of the flask. To the flask, there was then added 61 grams of aqueous sulfuric acid 20%) and the contents of the flask brought to a temperature of 85 C. and maintained at this temperature for about 95 minutes. At the end of this period of time, the contents of the flask were cooled below about 50 C. and discharged into a container as a resin-in-water dispersion having a solids content of 42 percent by weight.

Properties of the phenol-formaldehyde resin:

Mole ratio of reactants-formaldehyde to phenol 1.40 to 1 Number average molecular weight 350 Molecular weight distribution 3.96 Weight average molecular weight 1390 Amount of resin made up of one ring compounds percent 29 Amount of resin made up of one and two ring compounds percent" 52 *Gel time seconds 125 The size of the resin particles, dispersion thereof in the aqueous medium and the stability and dilutability char- 12' acteristics of the aqueous dispersion were comparable to those of Example 1.

pH of the aqueous dispersion 5.3 Pollution Index of the aqueous dispersion percent 3.4

EXAMPLE 15 Into a 12 liter reaction flask, equipped with a reflux condenser, thermometer and agitator, there was charged 3000 grams of phenol, 3000 grams of aqueous formaldehyde (40%), and 180 grams of hexamethylentetramine. The resultant mixture was heated to a temperature of C. under a pressure of 16-17 mm. of Hg and held at 80 C. for about 25 minutes. At the end of the 25 minute period, 60 grams of gum arabic, 15 grams of guar gum and 1800 grams of water were added to the flask in the order recited. The reaction mixture was held at a temperature of C. until the gel time of the product was about 60 seconds. At this point, 120 grams of hexamethylenetetramine were added to the flask and the reaction continued at a temperature of 85 C. to a product gel time of 25 seconds. The contents of the flask were cooled rapidly to below a temperature of 50 C. and discharged into a container as a resin-in-water dispersion having a soilds content of 42 percent by weight.

Properties of the phenol-formaldehyde resin:

Mole ratio of reactants-formaldehyde to phenol 1.26 to 1 Number average molecular weight 340 Weight average molecular weight 723 Molecular weight distribution 2.13

Amount of resin made up of one ring compounds percent by wt.-- 29.5 Amount of resin made up of one and two ring compounds percent by wt.-- 53.0 Gel time seconds 25 The size of the resin particles, dispersion thereof in the aqueous medium and the stability and dilutability characteristics of the aqueous dispersion were comparable to those of Example 1.

pH of the aqueous dispersion 7.6 Pollution Index of the aqueous dispersion percent 2.0

EXAMPLE 16 This example illustrates the use of the aqueous dispersions of the invention in the preparation of cellulosic products.

To a mixture of 65 grams of kraft paper pulp, 85 grams of the aqueous dispersion of Example 1 and 10,000 grams of water there was added sufficient alum to adjust the pH thereof to 4.5. The resin-pulp mixture was then collected on a mesh screen to form a sheet and then dried, at room temperature, to a moisture content of about 8 percent. The dried sheet was then hot pressed for 5 minutes at a pressure of 500 p.s.i.g. using platens which had been preheated to a temperature of 420 F.

A hard, rigid board was obtained, evidence of excellent bonding of the paper pulp fibers by the phenolic resin.

CONTROL 1 The procedure of Example 1 was repeated using as the sole gum, gum arabic. The actual materials used and amounts thereof are noted below.

Amount in grams The procedure of Example 1 was repeated using as the sole gum, guar gum. The actual materials used and amounts thereof are noted below:

Amount in grams Phenol 1200 Formaldehyde (40% aqueous solution) 1668 Barium hydroxide monohydrate 30 Guar gum 12 Water 920 Sulfuric acid (96.6%) Water 40 This formulation resulted in a water-in-resin dispersion rather than a resin-in-water dispersion. Consequently, the composition obtained could not be diluted with water and used in spray coating applications.

On the basis of 100 parts by weight phenol charged into the reaction flask, the amount of guar gum used was 1 percent by weight.

CONTROL 3 Example 1 was repeated with the exception that partSa by weight gum arabic were used, based on 100 parts of phenol charged.

Diluting the dispersion to 10% by Weight, on a solids basis, resulted in a rapid settling out of the particles.

CONTROL 4 Example 4 was repeated with the exception that no gums were used. No dispersion formed.

The term infinitely dilutable as used herein means that the aqueous dispersions can be diluted to a solids content of 1 percent by weight with no substantial change in the size and uniformity of the dispersed resin particles therein.

Recovery of the gums from the aqueous dispersions can be efi'ected by adding sufficient methyl isobutyl ketone to the dispersions to extract the phenolic resin, separating the organic phase (resin and methyl isobutyl ketone) from the water phase (gums and water) and recovering the gums by evaporating the water.

What is claimed is:

1. An aqueous dispersion containing dipersed particles of a heat-hardening resole phenolic resin in water and containing gum arabic and at least one of the following gums: a polysaccharide consisting essentially of mannose and galactose units and a polysaccharide consisting essentially of D-mannuronic and L-guluronic acid units, wherein the combined weight of the recited gums is about 0.5 to about 12 parts by weight per 100 parts by weight phenol used in producing the resin and the weight ratio of the gum arabic to the other recited gums is about 0.5 to about 20 to 1, wherein said aqueous dispersion is stable for a period of time in excess of about two weeks, and is infinitely dilutable with water.

2. An aqueous dispersion as defined in Claim 1 wherein the combined weight of the recited gums is about 0.5 to about 10 parts by weight and the weight ratio of gum arabic to the other recited gums is about 0.5 to about 16 to 1.

3. An aqueous dispersion as defined in Claim 1 wherein the combined weight of the recited gums is about 1.2 to 4.5 parts by weight and the weight ratio of gum arabic to the other recited gums is about 1 to about 5 to 1.

4. An aqueous dispersion as defined in Claim 1 containing gum arabic and at least one of the following gums: a guar gum, an algin gum and a locust bean gum.

5. An aqueous dispersion as defined in Claim 1 wherein the heat-hardenable phenolic resin has a gel time of about 20 to about 150 seconds.

6. An aqueous dispersion as defined in Claim 1 wherein in the heat-hardenable phenolic resin has a gel time of about 30 to about seconds.

7. An aqueous dispersion as defined in Claim 1 wherein the heat-hardenable phenolic resin is a phenol-formaldehyde resin.

8. An aqueous dispersion as defined in Claim 1 wherein the heat-hardenable phenolic resin is a barium hydroxide catalzyed phenol-formaldehyde resin.

9. An aqueous dispersion as defined in Claim 1 containing a silane.

10. An aqueous dispersion as defined in Claim 9 wherein the silane has the formula:

H HC H NHC H NHC H Si(OCH 11. An aqueous dispersion as defined in Claim 1 wherein the gums are gum arabic and a guar gum.

12. An aqueous dispersion as defined in Claim 1 wherein the gums are gum arabic and an algin gum.

13. An aqueous dispersion as defined in Claim 1 wherein the gums are gum arabic and a locust began gum.

References Cited UNITED STATES PATENTS 2,967,836 1/1961 Moffitt et a1 260-172 1,976,433 10/1934 Cheetham 260-293 1,855,384 4/1932 Cheetham 260-293 3,231,349 1/1966 Stalego 260-293 3,331,885 7/1967 Rider et al 260-293 3,616,181 10/1971 Stalego 260-293 3,702,798 11/1972 Shannon 260-293 2,021,027 11/ 1935 Snell et a1 106-205 WILLIAM H. SHORT, Primary Examiner E. WOODBERRY, Assistant Examiner US. Cl. X.R. 

